1. Field of the Invention
This invention relates to photography and to novel chemical compounds useful therein. More particularly, it relates to novel chemical compounds useful in the development of photosensitive silver halide materials and to photographic products, processes and compositions employing the same.
2. Description of the Prior Art
It has been known for quite some time that Meisenheimer complexes are formed from sym-trinitrobenzene (TNB), tertiary amines, and certain ketones; see, for example, J. Meisenheimer, Justus Liebigs Ann. Chem., 323, 205 (1902). More recently it has been shown that a Meisenheimer type, a bicyclic type and a tetracyclic type compound were formed as the main coloring matters of the reaction of acetone with 1,3,5-trinitrobenzene in an alkaline medium as reported by K. Kohashi et al, Chem. Pharm. Bull. (Tokyo), 18, 2151 (1970) and K. Kohashi et al, ibid., 19, 213 (1971) and T. Kabeya et al, ibid., 19, 645 (1971). Of interest in the latter reports was the discovery of the formation of a bicyclic compound in the reaction between acetone, picric acid and piperidine to yield the bicyclic nitronate salt. The reaction of other acyclic ketones with electron-deficient aromatics in the presence of secondary amines has been shown to yield similarly interesting bicyclic compounds; see, for example, M. J. Strauss et al, J. Org. Chem., 36, 856 (1971) and M. J. Strauss et al, ibid., 35, 383 (1970).
The use of certain simple reductone compounds as silver halide developing agents has been disclosed, e.g., in U.S. Pat. Nos. 2,691,589; 3,615,440; 3,664,835; 3,672,896; 3,690,872; and 3,816,137.
It has now been discovered that catalytic hydrogenation of certain of the aforementioned bicyclic nitronate compounds in the presence of an acylating agent yields acylated reductone derivatives which upon acidic or alkaline hydrolysis give materials possessing pronounced reductone-like properties. In addition, it has been found that this new class of bicyclic compounds including both the acylated reductone derivatives and their hydrolysis products are useful as reducing agents and as photographic silver halide developing agents.